For the decentralized supply of electrical, thermal and/or mechanical energy to businesses, for example, use is increasingly being made of cogeneration systems which are operated with a combustion machine in particular in the form of a micro gas turbine. Such micro gas turbines are gas turbines of the lower power class, that is, up to approximately 500 kW rated power. Cogeneration systems of this type comprise, in known embodiments, not only the combustion machine itself but also a power converter which can be driven by the combustion machine, in particular in the form of an electrical generator, and a waste-heat device for the utilization of the waste heat contained in the exhaust gas of the combustion machine.
The gas turbines have, between a compressor and a turbine, a burner in which fuel is oxidized or burned with an oxidant, generally with air. The required mixing of fuel and oxidant takes place in a burner head. This burner head is typically attached to a burner flange via which the fuel supply lines are also led. Downstream of the burner head there is positioned a combustion chamber. The burner head extends along a burner longitudinal axis and normally comprises multiple oxidant ducts arranged with a radial spacing to the burner longitudinal axis in a main body. Into the oxidant ducts there issues in each case one fuel nozzle, which according to the prior art is in the form of a nozzle lance. Here, in each case one nozzle lance is situated preferably coaxially in a respective oxidant duct. The nozzle lances are normally held on the burner flange, where they are oriented and mounted in an axial direction by means of a structural shoulder. The fixing of the burner nozzles is generally realized by means of plates which are screwed to the burner flange. Here, the nozzle lances are inserted into the combustion chamber via the individual oxidant ducts, which are situated in the burner flange and which are in the form of passage bores. The fuel supply is realized via individual hoses which are fed via an upstream external distributor ring or else have a fuel supply duct in the burner flange. In systems that have hitherto been realized, the fuel nozzles are produced from solid material.
Here, a high level of outlay in terms of manufacturing, assembly and disassembly are involved, along with increased cost outlay owing to the high number of individual components. In particular, the manufacture of the nozzle lances is expensive, because thin bores (1 to 4 mm diameter) over a length of several centimeters are required for conducting the fuel. Further disadvantages that have been identified are a high risk of leakage owing to individual seals with often small sealing surfaces for structural space reasons, a susceptibility to failure owing to the installation complexity, and the requirement for an external fuel distributor ring and individual holse and/or pipe connections from the fuel distributor ring to the fuel nozzles.